What do you need?
190g of alum per shell
450ml of hot water per shell
30 drops of watercolour
a straw
5 cups
Today we continue with the geodes but when weighing we find we've got just enough Alum for five shells. So later on we'll think about making something nice from the sixth shell.
Today we need help from an adult too, because of the Alum powder and the hot water.
How to make crystals
Weigh 190 grams Alum per shell and put it in a cup.
Add 450 ml almost boiling water to each cup.
Stir carefully until the Alum is completely dissolved.
Cut off a straw and stick it into the paint. Press the top shut.
Let go of the top above the cup. Drip in all your colours this way.
Place the shells in the cups wearing gloves, paint staines.
Blue, red, green and yellow will be your four colours, cup 5 is colourless.
After two days you see already some deposition of crystals. But we have patience and leave the shells a little longer in the containers.
After 4 days take the shells from the cups. Fill them up with hot water and stir the Alum on the bottom through. Place the shells back into the cups.
After exactly 7 days your shells are ready. Take them from the containers and let them drain on kitchen paper. Be careful, wet crystals are brittle!
The colours do vary slightly from the paint, see white, green and yellow.
and these are red and blue, but we think they're really AWESOME!